IL-6 is a pleiotropic cytokine with a wide range of biological activities. The IL-6 pathway functions through the interaction of IL-6 with its receptor IL-6R. This cytokine-receptor complex interacts with a third partner, the adaptor molecule glycoprotein 130 (gp130), responsible for signal transduction and activation of the cell (Jones et al. 2011, J. Clin. Investig. 121: 3375-83). IL-6R is present not only as a membrane bound form but also as a soluble form. sIL-6R can interact with IL-6 and this complex can activate gp130-positive cells without the presence of membrane-bound (m)IL-6R on the surface of the cells. This process is called trans-signaling and implies that mIL-6R negative cells are also susceptible to activation, with soluble IL-6R acting as an agonist (Jones et al. 2011; Waetzig and Rose-John 2012, Exp. Opinion Therap. Targets, 16: 225-36).
As IL-6 is a pleiotropic cytokine, its function is highly diverse. Many studies revealed that this molecule, by binding to the target IL-6R and gp130, plays a role in the immune, hematopoietic, hepatic, and neuronal systems (Maini 2008, Plenary lecture EULAR conference 2008; Jones et al. 2005, J. Interferon Cytokine Res. 25: 241-253).
Deregulation of IL-6 production is implicated in the pathology of several autoimmune and chronic inflammatory proliferative disease processes (Ishihara and Hirano 2002, Biochim. Biophys. Acta 1592: 281-96). IL-6 overproduction and signaling (and in particular trans-signaling) are involved in various diseases and disorders, such as sepsis (Starnes et al. 1999, J. Immunol. 148: 1968) and various forms of cancer such as multiple myeloma disease (MM), renal cell carcinoma (RCC), plasma cell leukemia (Klein et al. 1991, Blood 78: 1198-204), lymphoma, B-lymphoproliferative disorder (BLPD) and prostate cancer. Non-limiting examples of other diseases caused by excessive IL-6 production or signaling include bone resorption (osteoporosis) (Roodman et al. 1992, J. Bone Miner. Res. 7: 475-8; Jilka et al. 1992, Science 257: 88-91), cachexia (Strassman et al. 1992, J. Clin. Invest. 89: 1681-1684), psoriasis, mesangial proliferative glomerulonephritis, Kaposi's sarcoma, AIDS-related lymphoma (Emilie et al. 1994, Int. J. Immunopharmacol. 16: 391-6), inflammatory diseases and disorder such as rheumatoid arthritis (RA), systemic onset juvenile idiopathic arthritis (JIA), hypergammaglobulinemia (Grau et al. 1990, J. Exp. Med. 172: 1505-8), Crohn's disease, ulcerative colitis, systemic lupus erythematosus (SLE), multiple sclerosis, Castleman's disease, IgM gammopathy, cardiac myxoma, asthma (in particular allergic asthma) and autoimmune insulin-dependent diabetes mellitus (Campbell et al. 1991, J. Clin. Invest. 87: 739-742).
Rheumatoid arthritis (RA) is a chronic systemic inflammatory autoimmune disease that affects 0.5-1% of the population and is three times more prevalent in women than in men (Emery 2010, Int. J. Clin. Rheum. 5: 17-24). It is clinically characterized by joint pain, stiffness, and swelling due to synovial inflammation, leading to joint damage, deformity, severe disability, and increased mortality. Patients may develop multiple systemic symptoms including fever, fatigue, anemia, and osteoporosis.
Initial treatment options include disease-modifying anti-rheumatic drugs (DMARDs), non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, analgesics, surgery, physiotherapy, and occupational therapy. The synthetic DMARDs most commonly used include methotrexate (MTX), sulfasalazine, leflunomide, hydroxychloroquine, cyclosporine A, and glucocorticoids. The therapeutic benefits of DMARDs in RA include control of signs and symptoms, improvement of functional status and of quality of life, and retardation of joint damage progression (Firestein et al. 2006, Kelley's Textbook of Rheumatology (8th ed.) Elsevier, p. 1119-1143). MTX administered alone or in combination with another conventional DMARD, is the recommended first-line therapy for patients with RA (Coppieters et al. 2006, Arthritis Rheum. 54: 1856-1866).
For patients with an inadequate response to conventional DMARDs, biological drugs may be indicated. These biological drugs block certain key molecules that are involved in the pathogenesis of the illness. These targets include tumor necrosis factor alpha (TNFα), selective T-cell co-stimulation molecule (such as cytotoxic T-lymphocyte-associated protein 4), cluster of differentiation 20 (CD20), interleukin-1 (IL-1), IL-6, and interleukin-6 receptor (IL-6R). The development of immune-modulating agents has offered new treatment options for patients.
Although anti-TNFα agents and other biological DMARDs have been established as effective treatment options for RA, there are reasons to study the effectiveness of new therapeutic agents. For example, there is a subset of the patient population that does not achieve a clinical response, defined as American College of Rheumatology (ACR) 20 response, and only a small proportion achieve a high level ACR response (ACR50 or ACR70) (Dennis et al. 2002, J. Biol. Chem. 277: 35035-35043). Although therapy with biological DMARDs has been successful in the treatment of RA, certain patients may lose clinical response over time for various reasons such as disease burden, low drug serum levels, rapid clearance, and immunogenicity, in addition to other limitations with respect to safety, dosing regimen, and way of administration. Thus there is need for new therapeutic agents to address some of these limitations and to improve the effectiveness of biological agents in treating RA.
Systemic lupus erythematosus (SLE) or lupus, is a systemic autoimmune disease (or autoimmune connective tissue disease) that can affect any part of the body. As in other autoimmune diseases, the immune system attacks the body's cells and tissue, resulting in inflammation and tissue damage (James et al. 2005. Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders). Bound antibody-antigen immune complexes precipitate and cause a further immune response.
The clinical presentation of SLE can be very diverse and can include disorders of joints, skin, heart, lungs, blood vessels, liver, kidneys, and nervous system. The course of the disease is unpredictable, with periods of illness (called flares) alternating with remissions. The disease occurs nine times more often in women than in men, especially in women in child-bearing years ages 15 to 35, and is also more common in those of non-European descent. Even if life expectancy of such patients has improved, a patient in whom lupus is diagnosed at 20 years of age still has a 1 in 6 chance of dying by 35 years of age, most often from lupus or infection. Later, myocardial infraction and stroke become important causes of death (Rahman and Isenberg 2008, N. Engl. J. Med. 358: 929-939).
There is no cure for SLE. Due to the variety of symptoms and organ system involvement with SLE, its severity in an individual must be assessed in order to initiate treatment.
Disease-modifying antirheumatic drugs (DMARDs) are used preventively to reduce the incidence of flares, to reduce the progress of the disease, and to lower the need for steroid use. Flares, when they occur, are treated with corticosteroids (prednisone). DMARDs commonly in use are antimalarials such as hydroxychloroquine and immunosuppressants (e.g. mycophenolate mofetil, methotrexate, leflunomide, tacrolimus and azathioprine). Hydroxychloroquine is an antimalarial used for constitutional, cutaneous, and articular manifestations. Hydroxychloroquine has relatively few side effects and there is evidence that it improves survival in SLE. Cyclophosphamide is used for severe glomerulonephritis or other organ-damaging complications. Mycophenolic acid is also used for treatment of lupus nephritis, but it is not FDA-approved for this indication, and FDA is investigating reports that it may be associated with birth defects when used by pregnant women.
Depending on the dosage, people who require steroids may develop Cushing's syndrome, symptoms of which may include obesity, puffy round face, diabetes mellitus, increased appetite, difficulty sleeping and osteoporosis. These may subside if and when the large initial dosage is reduced, but long-term use of even low doses can cause elevated blood pressure and cataracts.
Numerous new immunosuppressive drugs are being actively developed to treat SLE. Rather than suppressing the immune system nonspecifically, as corticosteroids do, they target the responses of individual immune cells and individual types of immune cells. Belimumab (trade name BENLYSTA®, previously known as LymphoStat-B), is a human monoclonal antibody that inhibits B-cell activating factor (BAFF), also known as B-lymphocyte stimulator (BLyS), and was approved by the FDA in March 2011.
There remains a need for new therapeutic agents to address some of the above limitations and to improve the effectiveness in treating SLE.
Available therapies for the prevention or treatment of these IL-6 related diseases may not be effective for all patients and/or may lose effectiveness over time for various reasons such as disease burden, low drug serum levels, rapid clearance, and immunogenicity, in addition to other limitations with respect to safety, dosing regimen, and route of administration. Furthermore, available therapies to treat, for example, IL-6 related autoimmune conditions, may only be appropriate for acute care because longer-term use of these therapies (e.g. steroids) can lead to the development of secondary medical conditions requiring further treatment.
Thus, for the treatment of IL-6 related disease, including, for example, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), there is a need for new therapeutic agents to address the limitations of the available therapies and to improve the effectiveness of biological agents.
SEQ ID NO: 34 is a bivalent Nanobody consisting of two humanized and sequence-optimized variable domains derived from heavy chain-only llama antibodies. One domain (SEQ ID NO: 1) binds to IL-6R. The second domain (SEQ ID NO: 38) binds to human serum albumin (HSA). SEQ ID NO: 34 was extensively characterized in vitro (see for example WO 2010/115998).
A study assessing the safety, PK, PD, and efficacy after intravenous (i.v.) administration of SEQ ID NO: 34 in RA patients is described in WO 2013/041722. This placebo-controlled study included 28 subjects in an initial single ascending dose (SAD) part where single i.v. doses of 0.3, 1, 3, or 6 mg/kg were administered. In a subsequent multiple ascending dose (MAD) part, 37 subjects received multiple i.v. doses of 1 or 3 mg/kg every 4 weeks (q4w), or 6 mg/kg every 8 weeks, for 24 weeks in total. Dosing q4w at 3 mg/kg yielded the highest exposure, as indicated by the observed average trough levels (˜10 μg/mL), strongest biomarker response (based on sIL-6R profile), and the highest clinical remission rates.
Intravenous (i.v.) injections, however, are generally performed by the physician or by the medical professional staff. Therefore, the patient is expected to visit a health care professional regularly in order to receive treatment. Besides the discomfort created, the time taken up by this type of application often leads to unsatisfactory compliance by the patient, particularly for chronic diseases. Subcutaneous (s.c.) injection renders the possibility to the patient to self-administer the drug and consequently improve patients' convenience. These advantages are even more evident in the case of a long-term therapy, such as the treatment of rheumatoid arthritis and systemic lupus erythematosus.
Drawbacks of subcutaneous administration, however, include the incomplete bioavailability after subcutaneous administration (Richter et al. 2012, AAPS J. 14: 559-570; Macdonald et al. 2010, Curr. Opin. Mol. Ther. 12: 461-470) and the relative slow subcutaneous absorption (Zheng et al. 2012, MAbs 4: 243-255). For marketed IgG, the subcutaneous bioavailability estimates are mostly around 60-80% (Richter and Jacobsen 2014, Drug Metab. Dispos. 2014, Aug. 6). In addition, subcutaneous absorption of protein, particularly monoclonal antibodies is slow, as indicated by time to maximum serum concentrations (tmax) ranging usually from around 3 to up to 8 days in humans (Richter and Jacobsen 2014).
Following i.v. administration a biotherapeutic is directly injected into the systemic circulation. Following s.c. administration, however, the biotherapeutic is injected into the extracellular space of the subcutaneous tissue, from where it has to be absorbed by blood or lymph capillaries in order to reach the systemic circulation. These processes are influenced by properties of the biotherapeutic as well as by host factors (Richter et al., 2012). These pre-systemic events have to be considered in understanding the subcutaneous administration of biotherapeutics. Transport in the subcutis to the absorbing blood or lymph capillaries appears to be a major contributor to the slow subcutaneous absorption. Larger proteins (>20 kDa) are mostly absorbed via the lymphatic system, though potential species differences are not fully understood yet. Also the presystemic catabolism leading to incomplete bioavailability is poorly understood, both the involved enzymes and its translation across species. In view of these (poorly understood) factors that influence subcutaneous delivery of a biotherapeutic, the bioavailability and absorption rate of a new biotherapeutic upon subcutaneous administration cannot be predicted.
For IgGs, binding to neonatal Fc receptor (FcRn) appears important to obtain a high bioavailability. During s.c. absorption FcRn binding may prevent IgG from catabolism in subcutaneous tissue/lymphatics or may enhance the FcRn mediated transcytosis across the vascular endothelium (Richter et al., 2012). Subcutaneously administration of immunoglobulin single variable domains and their bioavailability and absorption rate has not yet been reported. These molecules do not possess an Fc region.